Hypertension (HTN) is a major health problem in the United States placing some 58 million Americans at increased risk for stroke, myocardial infarction, kidney failure, and peripheral vascular disease. African Americans are especially vulnerable, with hypertension affecting 36% of the adult black population. In addition, HTN is associated with subclinical changes in the heart (e.g., left ventricular hypertrophy) and in the brain (e.g., impairments of cognitive function). Although pharmacologic management of HTN is often effective, medications are not without complications and untoward side effects. Consequently, there has been a great deal of interest in the development and application of behavioral treatments for the management of HTN. The present study has three long term objectives. The first is to evaluate the efficacy of aerobic exercise in reducing blood pressure in Black men and women with mild-moderate HTN. The second is to investigate the mechanisms by which blood pressure is reduced, especially the effects of exercise on sodium retention and sympathetic activity. The third is to assess the effects of exercise on cognitive performance and related aspects of quality of life. Eighty unmedicated black subjects with mild HTN will be randomly assigned to 4 months of aerobic exercise or a waiting list control group. Subjects will undergo comprehensive evaluations at baseline and at 4 months including measurements of blood pressure in the clinic during exercise and mental stress testing. Blood pressures also will be obtained at 6 month follow-up. This project is designed to evaluate the effectiveness of exercise in lowering blood pressure in African Americans with mild-moderate HTN and to provide new information regarding the mechanisms associated with blood pressure reduction. In addition, new information of the effects of behavioral interventions on quality of life will be provided.